U.S. patent application number 15/730548 was filed with the patent office on 2018-05-10 for spectrometer with active beam steering.
The applicant listed for this patent is SpectraSensors, Inc.. Invention is credited to Douglas Beyer, Alfred Feitisch, Keith Benjamin Helbley, Xiang Liu.
Application Number | 20180128678 15/730548 |
Document ID | / |
Family ID | 53716591 |
Filed Date | 2018-05-10 |
United States Patent
Application |
20180128678 |
Kind Code |
A1 |
Feitisch; Alfred ; et
al. |
May 10, 2018 |
SPECTROMETER WITH ACTIVE BEAM STEERING
Abstract
A spectrometer includes a light source that emits a beam into a
sample volume comprising an absorbing medium. Thereafter, at least
one detector detects at least a portion of the beam emitted by the
light source. It is later determined, based on the detected at
least a portion of the beam and by a controller, that a position
and/or an angle of the beam should be changed. The beam emitted by
the light source is then actively steered by an actuation element
under control of the controller. In addition, a concentration of
the absorbing media can be quantified or otherwise calculated
(using the controller or optionally a different processor that can
be local or remote). The actuation element(s) can be coupled to one
or more of the light source, a detector or detectors, and a
reflector or reflectors intermediate the light source and the
detector(s).
Inventors: |
Feitisch; Alfred; (Los
Gatos, CA) ; Liu; Xiang; (Rancho Cucamonga, CA)
; Helbley; Keith Benjamin; (Rancho Cucamonga, CA)
; Beyer; Douglas; (Redlands, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SpectraSensors, Inc. |
Rancho Cucamonga |
CA |
US |
|
|
Family ID: |
53716591 |
Appl. No.: |
15/730548 |
Filed: |
October 11, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14466819 |
Aug 22, 2014 |
9816860 |
|
|
15730548 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 2201/062 20130101;
G01N 2201/06113 20130101; G01J 3/0205 20130101; G01J 3/0237
20130101; G01J 3/0278 20130101; G01N 21/31 20130101; G01J 2003/421
20130101; G01J 3/0291 20130101; G01J 3/42 20130101; G01J 3/027
20130101 |
International
Class: |
G01J 3/02 20060101
G01J003/02; G01J 3/42 20060101 G01J003/42; G01N 21/31 20060101
G01N021/31 |
Claims
1. An apparatus comprising: a light source configured to emit a
beam into a sample volume comprising an absorbing medium; at least
one detector positioned to detect at least a portion of the beam
emitted by the light source; at least one actuation element
configured to selectively cause the beam emitted by the light
source to be steered; and a controller coupled to the at least one
actuation element, the controller element configured to at least
cause the at least one actuation element to steer the beam to
adjust a position and/or an angle of the beam.
2. The apparatus of claim 1, wherein the at least one actuation
element is coupled to the light source and/or the at least one
detector.
3. (canceled)
4. The apparatus of claim 1, wherein the at least one actuation
element is coupled to a transmissive optical element and/or a
reflective optical element intermediate the light source and the at
least one detector.
5. The apparatus of claim 1, wherein the absorbing medium comprises
a gas, a liquid, a reflective media, an emitting media, and/or a
Raman active media.
6. The apparatus of claim 1, further comprising: a housing defining
the sample volume.
7. (canceled)
8. The apparatus of claim 1, wherein the at least one actuation
element comprises at least one piezo element.
9. The apparatus of claim 1, wherein the at least one actuation
element comprises a stepper motor, an electro-optical actuator, an
acousto-optical actuator, a micro-electro-mechanical systems (MEMS)
actuation device, an inch-worm, a mechanical actuator, a magnetic
actuator, an electrostatic actuator, an inductive actuator, a
rotary actuator, a heated actuator, a pressure actuator, a stress
and strain actuator, and/or an analog motor.
10. The apparatus of claim 1, wherein the at least one actuation
element comprises and/or is coupled to a prism, an etalon, a lens,
one or more gratings, a diffractive optical element, a reflector, a
birefringent element, a crystal element, an amorphous element, an
electro-optic element, an acousto-optic element, an optical window,
an optical wedge, a waveguide, an adjustable waveguide, an
electrically manipulated waveguide, and/or an air waveguide
11. (canceled)
12. The apparatus of claim 1, wherein the beam is steered based at
least on the angle and/or the position of the beam as detected by
at least one detector.
13. The apparatus of claim 1, wherein the steering of the beam to
comprises adjusting the position of the beam in accordance with a
pre-defined x-y position and/or adjusting the angle of the beam in
accordance with a pre-defined x-y angle.
14. (canceled)
15. The apparatus of claim 1, wherein the controller is further
configured to cause the at least one actuation element to maintain
the position of the beam at a pre-defined x-y position and/or
maintain the angle of the beam at a pre-defined x-y angle.
16. The apparatus of claim 1, wherein the at least one detector
comprises an array of photoreceivers, a multi-element
photoreceiver, and/or at least one position sensing photodiode.
17. (canceled)
18. (canceled)
19. The apparatus of claim 1, wherein the light source comprises a
tunable diode laser, a tunable semiconductor laser, a quantum
cascade laser, an intra-band cascade laser (ICL) a vertical cavity
surface emitting laser (VCSEL), a horizontal cavity surface
emitting laser (HCSEL), a distributed feedback laser, a light
emitting diode (LED), a super-luminescent diode, an amplified
spontaneous emission (ASE) source, a gas discharge laser, a liquid
laser, a solid state laser, a fiber laser, a color center laser, an
incandescent lamp, a discharge lamp, a thermal emitter, and/or a
device capable of generating frequency tunable light through
nonlinear optical interactions.
20. The apparatus of claim 1, wherein the at least one detector
comprises an indium gallium arsenide (InGaAs) detector, an indium
arsenide (InAs) detector, an indium phosphide (InP) detector, a
silicon (Si) detector, a silicon germanium (SiGe) detector, a
germanium (Ge) detector, a mercury cadmium telluride detector
(HgCdTe or MCT), a lead sulfide (PbS) detector, a lead selenide (Pb
Se) detector, a thermopile detector, a multi-element array
detector, a single element detector, a CMOS (complementary metal
oxide semiconductor) detector, a CCD (charge coupled device
detector) detector, and/or a photo-multiplier.
21. The apparatus of claim 6, wherein the housing defines a sample
cell that comprises of a multiple-pass configuration in which the
light is reflected between one or more optically reflective mirrors
while the light remains inside the sample cell, a multiple-pass
configuration in which the light is reflected and/or refracted by
one or more optical elements while the light remains inside the
sample cell, a Herriot Cell, an on-axis optical resonator, an
elliptical light collector, an at least one reflection multipass
cell, an off-axis optical resonator, a White cell, an optical
cavity, a hollow core light guide, and/or a single pass
configuration in which the light is not being reflected while the
light remains inside the sample cell.
22. The apparatus of claim 1, wherein the at least one actuation
element is coupled to a reflector, and wherein the at least one
actuation element is configured to selectively cause at least one
reflective property of the reflector to change.
23. The apparatus of claim 22, wherein the at least one actuation
element causes the reflector, the light source, and/or the at least
detector to translate along a z-axis to change an overall beam path
length.
24. (canceled)
25. (canceled)
26. (canceled)
27. The apparatus of claim 1, wherein steering of the beam
comprises changing an overall beam path length.
28. (canceled)
29. (canceled)
30. A method comprising: emitting, by a light source, a beam into a
sample volume comprising an absorbing medium; detecting, by at
least one detector, at least a portion of the beam emitted by the
light source; determining, by a controller, that a path of the beam
should be steered in response to detecting a divergence in the path
of the beam, an optical diffraction along the path of the beam,
and/or an interference along the path of the beam; and selectively
steering, by at least one actuation element coupled with
controller, the beam to adjust a position and/or an angle of the
beam, the position and/or angle of the beam being adjusted in order
to correct the divergence, the optical diffraction, and/or the
interference.
31. (canceled)
32. (canceled)
33. (canceled)
34. (canceled)
35. (canceled)
36. (canceled)
37. (canceled)
38. The apparatus of claim 1, wherein the beam is steered to
correct a divergence in a path of the beam, an optical diffraction
along the path of the beam, and/or an interference along the path
of the beam.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Continuation Application of
U.S. patent application Ser. No. 14/466,819, entitled "SPECTROMETER
WITH ACTIVE BEAM STEERING," and filed on Aug. 22, 2014, the
disclosures of which are incorporated herein by reference in their
entireties for all purposes.
TECHNICAL FIELD
[0002] The subject matter described herein relates to spectroscopic
analyzers in which a beam emitted by a light source is selectively
steerable using a controller.
BACKGROUND
[0003] Spectrometers use light emission or absorption or Raman
scattering by matter to qualify and quantify specific atoms and
molecules in analysis of gas, solid or liquid phase compounds. In
one case, the radiation emitted from a light source is absorbed
with a particular energy determined by optical transitions
occurring within the atoms, ions or molecules of an analyte. In
another case, the light emitted by atoms, ions or molecules of the
analyte is composed of spectral components of particular energy,
which are determined by optical transitions within the atoms or
molecules. In yet another case, light scattered by matter contains
spectral components which are created by Raman scattering,
corresponding to certain particular transitions in molecules or
ions. For example, in infrared absorption spectroscopy, discrete
energy quanta are absorbed by molecules due to excitation of
vibrational or rotational transitions of the intra-molecular
bonds.
[0004] Variations in environmental conditions as well as aging or
fouling of reflector surfaces in a spectrometer sample cell, or
replacement of fouled or deteriorated reflector surfaces can cause
a beam path of a light source within a spectrometer to change over
time or as a result of changing a reflector. Changes of the beam
path in an optical spectrometer can invalidate the spectrometer
calibration. In most cases, such spectrometers require factory
calibration of at least a sample cell or replacement by a skilled
technician. Such service calls and factory repairs are costly and
result in downtime for the spectrometer and the operation it
controls, while such repairs are being performed. This is a common
problem today with conventional TDL (tunable diode laser)
spectrometers which require a factory calibration of the sample
cell when at least one reflector in the cell has to be replaced due
to fouling or due to other deterioration of a reflecting surface.
The factory turn-around time of such a sample cell repair and
replacement has been precluding TDL spectrometers being used in
many petrochemical production processes, such as ethylene and
propylene production, due to unavoidable reactor upset conditions,
which result in liquids flowing through sample cells and leaving
damaging residue on reflectors.
SUMMARY
[0005] In one aspect, an apparatus is provided that includes a
light source, at least one detector, an actuation element, and a
controller coupled to the actuation element. The light source is
configured to emit a beam into a sample volume comprising an
absorbing medium. The at least one detector is positioned to detect
at least a portion of the beam emitted by the light source. The
actuation element is configured to selectively cause the beam
emitted by the light source to be steered. Concentration levels of
the absorbing medium and the like can be determined based on the
signal intensity detected by the at least one detector. In some
variations, there can be two or more actuation elements.
[0006] The actuation element can be coupled to the light source,
the at least one detector, a reflector intermediate the light
source and the detector, and/or to at least one transmissive or
reflective optical element intermediate the light source and the at
least one detector. The actuation element can be coupled to a
reflector and is configured to selectively cause at least one
reflective property of the reflector to change.
[0007] The absorbing medium can be one or more of: gas, liquid,
reflective media, emitting media, or Raman active media.
[0008] The apparatus can include a housing defining a sample
volume. Such a housing can be, for example, a multiple-pass
configuration in which the light is reflected between one or more
optically reflective mirrors while the light remains inside the
sample cell, a multiple-pass configuration in which the light is
reflected and/or refracted by one or more optical elements while
the light remains inside the sample cell, a Herriot Cell, an
on-axis optical resonator, an elliptical light collector, an at
least one reflection multipass cell, an off-axis optical resonator,
a White cell, an optical cavity, a hollow core light guide, or a
single pass configuration in which the light is not being reflected
while the light remains inside the sample cell.
[0009] In other variations, the sample volume forms part of an open
path system.
[0010] The actuation element can include at least one piezo
element. In other variations, the actuation element includes one or
more: stepper motors, electro-optical actuators, acousto-optical
actuators, an adjustable optical waveguide, a
micro-electro-mechanical systems (MEMS) actuation devices, a light
valve, an inch-worm, a mechanical actuator, a magnetic actuator, an
electrostatic actuator, an inductive actuator, a rotary actuator, a
heated actuator, a pressure actuator, a stress and strain actuator,
or an analog motor.
[0011] In some variations, the actuation element can include or be
coupled to one or more of a prism, an etalon, a lens, gratings, a
diffractive optical element, a reflector, a birefringent element, a
crystal element, an amorphous element, an electro-optic element, an
acousto-optic element, an optical window, an optical wedge, a
waveguide, an electrically manipulated waveguide, or an air
waveguide.
[0012] The controller can cause the light source to steer the beam
in response to a position and/or an angle that such beam is
detected by at least one detector. The beam (in response to signals
from the controller) can be steered to a pre-defined position and
angle along the at least one detector.
[0013] The at least one detector can include an array of
photoreceivers and/or it can be a multi-element photoreceiver. The
at least one detector can include at least one position sensing
photodiode.
[0014] The light source can include at least one of a tunable diode
laser, a tunable semiconductor laser, a quantum cascade laser, an
intra-band cascade laser (ICL) a vertical cavity surface emitting
laser (VCSEL), a horizontal cavity surface emitting laser (HCSEL),
a distributed feedback laser, a light emitting diode (LED), a
super-luminescent diode, an amplified spontaneous emission (ASE)
source, a gas discharge laser, a liquid laser, a solid state laser,
a fiber laser, a color center laser, an incandescent lamp, a
discharge lamp, a thermal emitter, or a device capable of
generating frequency tunable light through nonlinear optical
interactions.
[0015] The at least one detector can include at least one of an
indium gallium arsenide (InGaAs) detector, an indium arsenide
(InAs) detector, an indium phosphide (InP) detector, a silicon (Si)
detector, a silicon germanium (SiGe) detector, a germanium (Ge)
detector, a mercury cadmium telluride detector (HgCdTe or MCT), a
lead sulfide (PbS) detector, a lead selenide (Pb Se) detector, a
thermopile detector, a multi-element array detector, a single
element detector, a CMOS (complementary metal oxide semiconductor)
detector, a CCD (charge coupled device detector) detector, or a
photo-multiplier.
[0016] In another aspect, a light source emits a beam into a sample
volume comprising an absorbing medium. Thereafter, at least one
detector detects at least a portion of the beam emitted by the
light source. It is then determined, based on the detected at least
a portion of the beam and by a controller, that a position and/or
an angle of the beam should be changed. An actuation element under
control of a controller then causes the beam emitted by the light
source to be selectively steered.
[0017] The actuation element can be coupled to the light source and
cause a position and/or an angle of the light source to change. The
actuation element can be coupled to the at least one detector and
cause a position (along one or more of an x-axis, a y-axis, and a
z-axis) and/or an angle (along one or more of an x-axis, a y-axis,
and a z-axis) of the at least one detector to change. The actuation
element can be coupled to at least one reflector positioned
intermediate the light source and the at least one detector and
cause a reflective property of the at least one reflector to
change, including but not limited to angle, surface figure or
radius of curvature and the like. The actuation element can be
intermediate the light source and the at least one detector.
[0018] The actuation element can be coupled to at least one of a
transmissive or reflective optical element intermediate the light
source and the at least one detector. The actuation element in some
variations can be coupled to two or more of: (i) the light source,
(ii) the at least one detector, (iii) at least one reflector, or
(iv) the at least one transmissive or reflective light beam
actuation element intermediate the light source and the at least
one detector.
[0019] Beam steering as provided herein can include (unless
otherwise specified) changing an overall beam path length. For
example, the at least one actuation element can cause one or more
of a reflector, the light source, a transmissive element, the at
least one detector to translate along a z-axis to change the
overall beam path length.
[0020] In another aspect, a light source is caused to emit a beam
into a sample volume comprising an absorbing medium. Thereafter, a
signal is received from at least one detector that characterizes
detection of at least a portion of the beam emitted by the light
source. It is then determined, based on the received signal, that a
position and/or an angle of the beam should be changed. In
response, an actuation element is caused to selectively steer the
beam emitted by the light source.
[0021] The subject matter described herein provides many technical
advantages. For example, degradation of spectrometer calibration
fidelity and calibration offsets due to age and environmental
factors or due to reflector exchanges can be greatly reduced by
selectively steering the beam(s) which are emitted by a light
source or which are received by a detector to ensure optimal
performance and calibration fidelity. In particular, with the
current subject matter spectrometers can be repaired in the field
by replacing fouled or damaged components, without need for factory
realignment and recalibration. Furthermore, by providing active
beam steering, the current subject matter can be used to maintain
optimum optical throughput through a spectrometer thereby extending
an amount of time required between cleaning intervals. Furthermore,
active beam steering as provided herein can be used to counter
external influences such as temperature changes in the sample gas
and/or the environment, thermal expansion, index changes, Schlieren
effects, and the like which can cause the beam path to alter.
[0022] Non-transitory computer program products (i.e., physically
embodied computer program products) are also described that store
instructions, which when executed by one or more data processors of
one or more computing systems, causes at least one data processor
to perform operations herein. Similarly, computer systems are also
described that may include one or more data processors and memory
coupled to the one or more data processors. The memory may
temporarily or permanently store instructions that cause at least
one processor to perform one or more of the operations described
herein. In addition, methods can be implemented by one or more data
processors either within a single computing system or distributed
among two or more computing systems. Such computing systems can be
connected and can exchange data and/or commands or other
instructions or the like via one or more connections, including but
not limited to a connection over a network (e.g. the Internet, a
wireless wide area network, a local area network, a wide area
network, a wired network, or the like), via a direct connection
between one or more of the multiple computing systems, etc.
[0023] The details of one or more variations of the subject matter
described herein are set forth in the accompanying drawings and the
description below. Other features and advantages of the subject
matter described herein will be apparent from the description and
drawings, and from the claims. It should be noted that the current
subject matter contemplates both a closed sample cell and an open
path system for detecting trace gases and/or liquids. The terms
"sample gas volume", "gas volume", "sample liquid volume" and
"liquid volume" as used herein therefore refers to either a flowing
volume or a static, batch volume of gas or liquid (as the case may
be).
DESCRIPTION OF DRAWINGS
[0024] The accompanying drawings, which are incorporated in and
constitute a part of this specification, show certain aspects of
the subject matter disclosed herein and, together with the
description, help explain some of the principles associated with
the disclosed implementations. In the drawings,
[0025] FIG. 1 is a process flow diagram illustrating selective
steering of a beam within a spectrometer;
[0026] FIG. 2 is a diagram illustrating a first spectrometer with a
sample cell;
[0027] FIG. 3 is a diagram illustrating a second spectrometer with
a sample cell;
[0028] FIG. 4 is a diagram illustrating a third spectrometer with a
sample cell;
[0029] FIG. 5 is a diagram illustrating a first open path
spectrometer;
[0030] FIG. 6 is a diagram illustrating a second open path
spectrometer; and
[0031] FIG. 7 is a diagram illustrating a second open path
spectrometer.
[0032] When practical, similar reference numbers denote similar
structures, features, or elements.
DETAILED DESCRIPTION
[0033] To address the aforementioned and other potential issues due
to beam position sensitivity with spectroscopic measurements,
implementations of the current subject matter can provide a
spectrometer having a light source with the ability to actively
steer its beam(s) or a portion thereof on its path through a
measurement sample onto a detector. As used herein (unless
otherwise specified), steering refers to changing the angle of the
beam path, the length of the beam path, and/or a position or angle
of a device forming part of a spectrometer. Gas and/or liquid
sampled from a source can include absorbing media (e.g., one or
more analyte compounds, etc.). Detection and/or quantification of
the concentration of such absorbing media can be performed by
spectroscopic analysis. The spectrometer can include at least one
actuation element that causes a beam path of the beam(s) emitted by
the light source to change as specified by a controller. In some
variations, the system can include spatial detectors/detector
arrays so that a control unit can determine a spatial and/or an
angular position of the beam and cause the actuation element to
make any required changes.
[0034] Analyte compounds with which implementations of the current
subject matter can be used include, all gas, liquid and solid phase
atoms, molecules and ions, which absorb light, but are not limited
to, hydrogen sulfide (H.sub.2S); hydrogen chloride (HCl); water
vapor (H.sub.2O); hydrogen fluoride (HF); hydrogen cyanide (HCN);
hydrogen bromide (HBr); ammonia (NH.sub.3); arsine (AsH.sub.3);
phosphine (PH.sub.3); oxygen (O.sub.2); carbon monoxide (CO);
carbon dioxide (CO.sub.2); chlorine (Cl.sub.2); nitrogen (N.sub.2),
hydrogen (H.sub.2); hydrocarbons, including but not limited to
methane (CH.sub.4), ethane (C.sub.2H.sub.6), ethylene
(C.sub.2H.sub.4), acetylene(C.sub.2H.sub.2), etc.; fluorocarbons;
chlorocarbons; alcohols; ketons; aldehydes; acids, bases and the
like.
[0035] FIG. 1 is a process flow diagram 100 in which, at 110, a
light source emits a beam into a sample volume comprising an
absorbing medium. Thereafter, at 120, at least one detector detects
at least a portion of the beam emitted by the light source. It is
later determined, at 130, based on the detected at least a portion
of the beam and by a controller, that a position and/or of the beam
as detected by the detector should be changed. The beam emitted by
the light source is then, at 140, actively steered by at least one
actuation element under control of the controller. In addition, a
concentration of the absorbing media can be quantified or otherwise
calculated (using the controller or optionally a different
processor that can be local or remote). The actuation element(s)
can be coupled to one or more of the light source, a detector or
detectors, and a reflector or reflectors intermediate the light
source and the detector(s) (although it will be appreciated that a
reflector is not required for all variations).
[0036] FIGS. 2-7 are diagrams 200-700 that show example
spectrometers for implementing the current subject matter. While
the following is described in connection with detecting absorbing
media within gas, it will be appreciated that the current subject
matter can also be applied to detecting absorbing media within
liquid. A light source 205 provides a continuous or pulsed light
that is directed to a detector 210 via a path length 215. The light
source 205 can include, for example, one or more of a tunable diode
laser, a tunable semiconductor laser, a quantum cascade laser, an
intra-band cascade laser (ICL), a vertical cavity surface emitting
laser (VCSEL), a horizontal cavity surface emitting laser (HCSEL),
a distributed feedback laser, a light emitting diode (LED), a
super-luminescent diode, an amplified spontaneous emission (ASE)
source, a gas discharge laser, a liquid laser, a solid state laser,
a fiber laser, a color center laser, an incandescent lamp, a
discharge lamp, a thermal emitter, and the like. The detector 210
can include, for example, one or more of an indium gallium arsenide
(InGaAs) detector, an indium arsenide (InAs) detector, an indium
phosphide (InP) detector, a silicon (Si) detector, a silicon
germanium (SiGe) detector, a germanium (Ge) detector, a mercury
cadmium telluride detector (HgCdTe or MCT), a lead sulfide (PbS)
detector, a lead selenide (Pb Se) detector, a thermopile detector,
a multi-element array detector, a single element detector, a
photo-multiplier, a CMOS (complementary metal oxide semiconductor)
detector, a CCD (charge coupled device detector) detector and the
like.
[0037] The path length 215 can traverse one or more volumes. In the
example systems 200-500 shown in FIGS. 2-7, the path length 215 can
twice traverse a volume 220 of an optical cell 225 that includes a
window or other at least partially radiation transmissive surface
230 and a reflector (e.g., a mirror, etc.) 235 or other at least
partially radiation reflective surface that at least partially
defines the volume 220. Sample gas can, in some implementations, be
obtained from a gas source, which in the examples of FIGS. 2 and 3
is a pipeline 240, for delivery to the volume 220, for example via
a sample extraction port or valve 245 that receives the sample gas
from the source. Gas in the volume 220 can exit via a second outlet
valve or port 250.
[0038] As illustrated in FIGS. 2-4, in some variations, the volume
220 can be part of a housing that defines a sample cell that can
be, for example, one or more of a Herriott Cell, an off-axis
optical resonator, an on-axis optical resonator, an elliptical
light collector, a White cell, an optical cavity, a hollow core
light guide, a multiple pass configuration in which the light beam
is reflected at least once or a single pass configuration in which
the light is not being reflected while the light traverses the
sample cell. In other variations, as illustrated in FIGS. 5-7, the
volume 220 can be part of an open path system that does not include
a dedicated sample cell. Open path systems can be used for various
applications including atmospheric pollutant studies, fence line
monitoring, process line/tank leak detection, industrial gas-purity
applications, and monitoring and control of combustion processes,
especially on exhaust stacks.
[0039] A controller 255, which can include one or more programmable
processors or the like, can communicate with one or more of the
light source 205, the detector 210, and the reflector 235 for
controlling the emission of the light 215 and receiving signals
generated by the detector 210 that are representative of the
intensity of light impinging on the detector 210 as a function of
wavelength. In various implementations, the controller 255 can be a
single unit that performs both of controlling the light source 205
and receiving signals from the detector 210, or it can be more than
one unit across which these functions are divided. Communications
between the controller 255 or controllers and the light source 205
and detector 210 can be over wired communications links, wireless
communications links, or any combination thereof. The controller
255 can also, in some cases, be used to quantify an amount of
absorbing media using the signal generated by the detector 210. In
other variations, the quantification can be determined by at least
one remote data processor.
[0040] An actuation element 260 (or two or more actuation elements
260) can be coupled to one or more of (i) the light source 205,
(ii) the detector 210, or (iii) the reflector 235, and the
controller 255. The controller 255 can send a signal to the
actuation element 260 to cause it to selectively steer (i.e.,
change trajectory of, etc.) the beam emitted by the light source
205 as detected by the detector 210. In some variations, the
actuation element 260 can be any device that causes a position of
the light source 205 to physically move and/or its beam angle to
physically change (and as such the actuation element 260 is not
intermediate either of the beam path, on one hand, and the light
source 205 and the detector 210, on the other hand). For example,
with this variation, the actuation element 260 can be/include at
least one piezo actuator element, an inch-worm, a mechanical
actuator, a magnetic actuator, an electrostatic actuator, an
inductive actuator, a rotary actuator, a heated actuator, a
pressure actuator, a stress and strain actuator, an analog motor, a
stepper motor, an electro-optical actuator, an acousto-optical
actuator, an adjustable wave guide and/or a
micro-electro-mechanical systems (MEMS) actuation device. Such
actuation elements 260 can cause at least a portion of the light
source 205 to move along the x-axis, the y-axis, the z-axis (or a
combination of two or more dimensions). With this variation,
location of the beam origin (laser location) can be changed with
respect to the sample cell (having an entrance hole and an exit
hole).
[0041] In some variations, the actuation element 260 can be any
device that causes a position and/or the angle of the detector 210
to physically move (and as such the actuation element 260 is not
intermediate either of the beam path, on one hand, and the light
source 205 and the detector 210, on the other hand). For example,
with this variation, the actuation element 260 can be/include at
least one piezo actuator element, an inch-worm, a mechanical
actuator, a magnetic actuator, an electrostatic actuator, an
inductive actuator, a rotary actuator, a heated actuator, a
pressure actuator, a stress and strain actuator, an analog motor, a
stepper motor, an electro-optical actuator, an acousto-optical
actuator, an adjustable waveguide and/or a micro-electro-mechanical
systems (MEMS) actuation device. Such actuation elements 260 can
cause at least a portion of the detector 210 to move along the
x-axis, the y-axis, the z-axis (or a combination of two or more
dimensions). Movement along the z-axis can cause the overall beam
length to be changed (reduced or increased).
[0042] In addition or in the alternative (as shown in FIGS. 3 and
6), the actuation element 260 can be placed intermediate the light
source 205 and the detector 210 and/or to intersect the beam path.
With such an arrangement, the actuation element 260 can be any
device/element that optically causes at least a portion of the beam
emitted by the light source 205 to selectively move and/or change
its beam angle (in some cases without moving the light source 205).
With this latter variation, the actuation element 260 can
be/include/be coupled to at least one of a prism, an etalon, a lens
and/or gratings, a diffractive optical element, a reflector, a
birefringent element, a crystal element, an amorphous element an
electro-optic element, an acousto-optic element, an optical window,
an optical wedge, and a waveguide such as an electrically
manipulated waveguide (e.g., solid state waveguides in which
refractive index patterns can be changed by applying localized
electrical fields and/or currents, etc.) or an air waveguide. With
regard to the latter, an air waveguide refers to manipulation of
the refractive index of air using one or more lasers or other light
sources (for example, by selectively pulsing the laser(s) to heat
air, etc.) which can, in turn, be used for beam steering. Some or
all of the actuation elements 260 can move in at least one of
x-axis, the y-axis, or the z-axis.
[0043] As described above, in some variations, the reflector(s) 235
can be translated in x,y, and/or z direction or its angle can be
changed with respect to the incident light beam and/or their
reflective properties, including but not limited to radius of
curvature and surface figure at the location of the incident light
beam can change to steer the beam emitted by the light source 205.
For example, an actuation element 260 can be/include at least one
piezo actuator element, an inch-worm, a mechanical actuator, a
magnetic actuator, an electrostatic actuator, an inductive
actuator, a rotary actuator, a heated actuator, a pressure
actuator, a stress and strain actuator, an analog motor, a stepper
motor, an electro-optical actuator, an acousto-optical actuator, an
adjustable waveguide and/or a micro-electro-mechanical systems
(MEMS) actuation device can cause the position and/or the angle of
the reflector 235 to change (which in turn changes the position of
the beam path). In other cases, the reflector 235 can comprise
adaptive optics having actuable reflecting surfaces. Such an
adaptive optical element can be a reflector made from a thin
reflecting foil, with the actuation element 260 mounted or printed
onto the backside of the reflector 235 in a multiplicity of
locations. Such mirrors can provide for active changes of the
reflecting surface in arbitrary fashion which, in turn, allows for
steering of the beam emitted by the light source 205 (via the
controller 255).
[0044] In some variations, the controller 255 can make a
determination that a beam path should be steered based on an
intensity level detected by the detector 210 without reference to
spatial location of such beam. For example, the intensity level can
indicate that a center of the beam has diverged and/or that there
is some optical diffraction or interference along the beam path.
The intensity level detected by the detector 210 can be compared to
a single intensity value at a single light frequency and/or
detected intensity can be compared to a frequency profile (which
can be generated during calibration of the spectrometer, etc.).
Deviations from such preset frequency or the frequency profile can
be used to trigger beam steering.
[0045] In addition or in the alternative, the controller 255 can
make a determination that a beam path should be steered based on a
position of the beam as detected by the detector 210. With such
latter variations, an array of photoreceivers and/or a detector
with an array of cells can be used. For example, the detector 210
can be a quad cell detector and/or a position sensing photodiode,
or a linear or 2D array of photoreceivers. With the example of a
quad cell detector, the position of the center point of the emitted
beam can be determined by a comparison of the detected signals from
each cell. Horizontal position of the center point can be
calculated by
[(cell.sub.2+cell.sub.4)-(cell.sub.1+cell.sub.3)]/(cell.sub.1+cell.sub.2+-
cell.sub.3+cell.sub.4) and the vertical position of the center
point can be calculated by
[(cell.sub.1+cell.sub.2)-(cell.sub.3+cell.sub.4)]/(cell.sub.1+cell.sub.2+-
cell.sub.3+cell.sub.4). In another example, the position sensitive
detector can be a detector which detects the x and y position as
well as the x and y angles of the beam. Furthermore, a
multi-element linear detector array can be used to determine the
beam position. In another variation, a 2-dimensional detector array
can be used to determine the beam position. With such spatially
sensitive detectors, a pre-defined position (along two or more
dimensions) and/or pre-defined angle (as specified by two or more
dimensions) can be maintained via the controller 255 and the
actuation element 260.
[0046] The volume 220 can be maintained at a stable temperature and
pressure. Alternatively, the volume 220 can include one or more
temperature and/or pressure sensors to determine a current
temperature and pressure within that volume for use in one or more
calculations to compensate for temperature and/or pressure changes
relative to a validation or calibration condition of the
spectroscopic instrument. Furthermore, the volume 220 can be
adjusted to preset temperature and pressure by heating elements and
pressure control elements or mass flow controllers.
[0047] The controller 255, or alternatively one or more other
processors that are either collocated with the other components or
in wireless, wired, etc. communication therewith, can perform the
processing functions discussed above in reference to the method
illustrated in FIG. 1.
[0048] One or more aspects or features of the subject matter
described herein can be realized in digital electronic circuitry,
integrated circuitry, specially designed application specific
integrated circuits (ASICs), field programmable gate arrays (FPGAs)
computer hardware, firmware, software, and/or combinations thereof.
These various aspects or features can include implementation in one
or more computer programs that are executable and/or interpretable
on a programmable system including at least one programmable
processor, which can be special or general purpose, coupled to
receive data and instructions from, and to transmit data and
instructions to, a storage system, at least one input device, and
at least one output device. The programmable system or computing
system may include clients and servers. A client and server are
generally remote from each other and typically interact through a
communication network. The relationship of client and server arises
by virtue of computer programs running on the respective computers
and having a client-server relationship to each other.
[0049] These computer programs, which can also be referred to as
programs, software, software applications, applications,
components, or code, include machine instructions for a
programmable processor, and can be implemented in a high-level
procedural language, an object-oriented programming language, a
functional programming language, a logical programming language,
and/or in assembly/machine language. As used herein, the term
"machine-readable medium" refers to any computer program product,
apparatus and/or device, such as for example magnetic discs,
optical disks, memory, and Programmable Logic Devices (PLDs), used
to provide machine instructions and/or data to a programmable
processor, including a machine-readable medium that receives
machine instructions as a machine-readable signal. The term
"machine-readable signal" refers to any signal used to provide
machine instructions and/or data to a programmable processor. The
machine-readable medium can store such machine instructions
non-transitorily, such as for example as would a non-transient
solid-state memory or a magnetic hard drive or any equivalent
storage medium. The machine-readable medium can alternatively or
additionally store such machine instructions in a transient manner,
such as for example as would a processor cache or other random
access memory associated with one or more physical processor
cores.
[0050] To provide for interaction with a user, one or more aspects
or features of the subject matter described herein can be
implemented on a computer having a display device, such as for
example a cathode ray tube (CRT) or a liquid crystal display (LCD)
or a light emitting diode (LED) monitor for displaying information
to the user and a keyboard and a pointing device, such as for
example a mouse or a trackball, by which the user may provide input
to the computer. Other kinds of devices can be used to provide for
interaction with a user as well. For example, feedback provided to
the user can be any form of sensory feedback, such as for example
visual feedback, auditory feedback, or tactile feedback; and input
from the user may be received in any form, including, but not
limited to, acoustic, speech, or tactile input. Other possible
input devices include, but are not limited to, touch screens or
other touch-sensitive devices such as single or multi-point
resistive or capacitive trackpads, voice recognition hardware and
software, optical scanners, optical pointers, digital image capture
devices and associated interpretation software, and the like.
[0051] In the descriptions above and in the claims, phrases such as
"at least one of" or "one or more of" may occur followed by a
conjunctive list of elements or features. The term "and/or" may
also occur in a list of two or more elements or features. Unless
otherwise implicitly or explicitly contradicted by the context in
which it is used, such a phrase is intended to mean any of the
listed elements or features individually or any of the recited
elements or features in combination with any of the other recited
elements or features. For example, the phrases "at least one of A
and B;" "one or more of A and B;" and "A and/or B" are each
intended to mean "A alone, B alone, or A and B together." A similar
interpretation is also intended for lists including three or more
items. For example, the phrases "at least one of A, B, and C;" "one
or more of A, B, and C;" and "A, B, and/or C" are each intended to
mean "A alone, B alone, C alone, A and B together, A and C
together, B and C together, or A and B and C together." In
addition, use of the term "based on," above and in the claims is
intended to mean, "based at least in part on," such that an
unrecited feature or element is also permissible.
[0052] The subject matter described herein can be embodied in
systems, apparatus, methods, and/or articles depending on the
desired configuration. The implementations set forth in the
foregoing description do not represent all implementations
consistent with the subject matter described herein. Instead, they
are merely some examples consistent with aspects related to the
described subject matter. Although a few variations have been
described in detail above, other modifications or additions are
possible. In particular, further features and/or variations can be
provided in addition to those set forth herein. For example, the
implementations described above can be directed to various
combinations and subcombinations of the disclosed features and/or
combinations and subcombinations of several further features
disclosed above. In addition, the logic flows depicted in the
accompanying figures and/or described herein do not necessarily
require the particular order shown, or sequential order, to achieve
desirable results. Other implementations may be within the scope of
the following claims.
* * * * *